Signal transmission lines (‘transmission lines’) are ubiquitous in modern communications. These transmission lines transmit electromagnetic (EM) signals (‘signals’) from point to point, and take on various known forms including stripline, microstripline (‘microstrip’), and coaxial (“coax”) transmission lines, to name a few.
It is desirable for these transmission lines to support a single eigenmode (‘single mode’) of signal propagation. Multi-mode signal propagation is problematic because the desired propagation mode and higher-order modes may interfere with each other to provide a received signal that is severely frequency-dependent in an uncontrolled and usually un-interpretable manner. This is analogous to the well-known multipath problem in wireless propagation, except in this instance the problem occurs in a “wired” setting. In high-bandwidth, high-quality signal environments multi-mode signal propagation is typically unacceptable.
What is needed, therefore, is a transmission line that fosters discrimination of a desired TEM mode of signal propagation from the higher-order modes.